Lasers have been used for several decades in the treatment of glaucoma. The 2 most common laser treatments for primary open angle glaucoma (POAG) are ALT (Argon Laser Trabeculoplasty) and SLT (Selective Laser Trabeculoplasty). See for example U.S. Pat. Nos. 3,884,236; 8,066,696; 5,549,596; 6,319,274. They work by applying laser pulses into the Trabecular Meshwork (in the anterior angle of the eye). These laser pulses are focused to around 50 micrometer diameter for ALT and around 400 micrometer for SLT. Those laser spots are targeted to lay over Schlemm's canal and cause an increased outflow through the treated Trabecular meshwork area. In both procedures at least 180 degrees of the eye angle is treated with typically 50 to 100 laser pulses (each pulse is applied to a new target zone-treatment area). The working mechanism for ALT is blanching of the Trabecular meshwork that increases the outflow by stretching the Trabecular Meshwork between the blanched (laser treated areas). The ALT laser with a typical setting of 600 mW and 0.1 s pulse duration (at 514 nm or 532 nm) causes a thermal tissue interaction. In SLT treatment the laser causes cavitation bubbles in the target tissue due to its shorter pulse duration of about 3 nanoseconds and higher peak power (created by pulse energies of around 0.3 mJ to 1.6 mJ).
Both procedures have a good success rate by increasing aqueous humor outflow that creates a substantial drop in intraocular pressure of around 20%. Both procedures can be performed in minutes with a simple slit lamp procedure in the office (no OR visit required). In both procedures, the eye does not need to be opened (non-invasive procedure), therefore the treatment risks and complication rates are minimal. The problem of these procedures as published in many studies is that it does not work effectively in all patients and in the successful cases the effect wears off over the course of a few (1-3 years) and the IOP rises back to its baseline level. The procedure can be repeated once with ALT and 2-3 times with SLT, but after those repeats the tissue damage in the Trabecular meshwork that is created through those multiple procedures ultimately prevents any further IOP lowering effect.
A less frequently used laser procedure called ELT (Excimer Laser Trabeculostomy) uses an Excimer laser pulse (wavelength in the UV range) to actually drill holes into the Trabecular Meshwork. See for example U.S. patent applications: 20080082078; 20040082939. Because complete openings are created to Schlemm's canal (unlike ALT and SLT), the IOP lowering effect is similar or better than ALT/SLT and in the same time only a few open holes need to be drilled with ELT versus 50-100 treatment zones in a typical ALT/SLT procedure. Some studies further suggest that the ELT effect is longer lasting then ALT/SLT due to some observed long term patency of those holes. Furthermore ELT might be repeated more often since a smaller area of the Trabecular Meshwork is treated each time. The downside of ELT is the fact that UV wavelength light does not penetrate the cornea and aqueous humor, therefore the laser can only be applied to the Trabecular Meshwork in an operating room procedure, where the eye is opened and a fiber probe is inserted into the anterior chamber all the way up to the Trabecular Meshwork.
In recent years the effectiveness of having one or multiple holes in the Trabecular Meshwork (connecting to Schlemm's canal) has also been demonstrated with several implants, placed through the Trabecular Meshwork that create an opening into Schlemm's canal. See for example U.S. patent applications: 20120071809, 20070276316. Those are however also invasive (full operating room) procedures using an implant.
Another approach to drain aqueous humor out of the anterior chamber has been successfully demonstrated by implanting a drainage tube through the scleral spur region and into the suprachoroidal space. See for example U.S. patent application: 20110098629. This is however also an invasive (full operating room) procedures using an implant.
Most recently, there have been animal tissue studies applying ultrashort photodisruptive laser pulses to the trabecular meshwork with limited success. Hiroshi Nakamura et. al. Investigative Ophthalmology & Visual Science, March 2009, Vol. 50, No. 3. Performed an ex vivo study on primates delivering photodisruptive laser pulses into the anterior angle of the eye. He presents several limitations and challenges in the paper concerning the goal of creating a hole through the Trabecular Meshwork. These limitations and challenges have so far prevented a successful use of such a non-invasive laser procedure in the angle of the eye.
The inventions described herein relate to a new devices and methods to overcome those limitations and challenges and therefore allow the creation of holes and channels in the Trabecular Meshwork and other places in the angle of the eye in a non-invasive procedure that can be repeated as many times as necessary.
Other examples of related prior art are U.S. Pat. Nos. 8,056,564; 4,391,275; 5,288,288; 7,912,100